Homebrew PCBs

Well, I finaly got around to buyng a jug of acid and trying this out.

I bought a gallon of HCL (31.25%) from my local hardware store, $2.95 
(USD) Stopped by the Pharmacy and bought a quart of 3% H2O2 for 
$0.94. 

Plastic container, about 1/4 cup acid, stuck in a piece of circuit 
board and started adding H2O2. At about 1/2 cup I could see some 
green tinge and the copper started changing. I poured in a litle more 
(about 3/4 cup total) and the copper etched in about 8 minutes.

About 1 cup total of etchant removed about 30 sq inches of copper 
(surplus scrap, but I think 1 oz) before it was quite dark and slowed 
considerably.

I think the amount of water in medical grade would prevent it being 
used to recharge the etchant (to much dilution) but it certainly 
started it fine. 

Even if I had to throw it away instead of recharging it, this is 
still *much* cheaper than Feric Chloride. At these ratios a 94 cent 
quart of medical H2O2 and a cup of acid would replace a $12 quart of 
Feric Chloride. 

I did notice that it was much more unpleasant to be around (lots of 
nasty fumes) But I can work around that.

Thanks
-Denny

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> On Tue, 06 Jan 2004 05:28:53 -0000, dkesterline <desterline@t...> 
wrote:
> 
> >> for a start you make a 15% HCl solution (tap water is fine)
> >>
> > Like 850cc water and 150cc hydrochloric acid? (clearifing 
weight / 
> > volume, and initial strength of the acid.)
> 
> i did it by volume, it is not critical.
> i think the recepie i read was 12% by volume.
> it doesn't change much.
> 
> many recepies call for 30% HCl diluted 1:1 (volume) with water.
> i think i did exactly that.
> 
> As it was said you can keep the acid amount low, and only let the 
CuCl2 do 
> all the
> work. but then you might experience the "blue" effect more often.
> 
> >
> >> Then you put a pcb in it.
> >>
> > One you want to etch, or just some scrap to start the proccess?
> 
> one you want to etch.
> but you can try it with scrap if you have too much ;-)
> no, it workes like always, also with the first pcb.
> i used the first one.
> 
> >
> >> then you put H2O2 in it.
> >> for the first pcb you may need more than usual.
> >
> > Approx how much? (please specify strength for that amount)
> 
> I don't remember clearly.
> if you have have 250ml etchant the smallest amount you can pour out 
of the 
> bottle will do.
> maybe a teaspoon full, or two.
> start slow, if it doesn't work use more, agitate in between.
> 
> 
> >
> > Any attempt to remove the copper in the long run? Or do you 
dispose and 
> > start over every so often?
> >
> no attempt yet.
> maybe some electroplating could work.
> but maybe all you get is cloring gas....
> 
> i think it would require carbon electrodes, stainless steel is 
definitely
> etched (ask the sink, now it has "freckles" where the tiny 
splatters around 
> the
> bowl landed...)
> 
> 
> >> For me this etchant is ideal with toner transfer - as it is as 
easy
> > and
> >> fast.
> >> the toner takes no harm in the etchant.
> >> photoresist works too.
> >> Most ohp markers (edding etc) don't work too well.
> >> the best is the red staedtler ohp pen ink.
> >
> > (assuming ohp = overhead projector) I thought OHP makers were 
water 
> > based. I've always used permanent markers like sharpies for this 
job. 
> > (though my toner transfer is almost good enough to not need it 
anymore :-)
> >
> 
> i used it once in my first 5 or so toner transfer boards.
> and then it was for the board outline ;-).
> 
> > I'm probably being overly analytical about this, it's likley the 
proccess 
> > is more forgiving and tolerant. But it's better to before I stir 
up a 
> > mess.
> >
> 
> i think so..
> the german recepies are rather crude, and i am always up for 
experiments...
> 
> 
> wear the proper protective things, goggles and maybe gloves.
> old clothes maybe, but if you mess around enough to stain your 
clothes
> maybe this is not the best thing to do...
> 
> but still - even if you ruin your clothes, not much harm done,
> if you ruin your eyes - you can't dispose of them and wear a new 
pair.
> so take the google thing serious.
> 
> Stefan
> 
> > Thanks
> > -Denny
> >
> >